Thermoplastic olefin films are widely used in many fields. Particular combinations of properties can be beneficial here, depending on the application sector. By way of example, thermoplastic olefin roofing membranes can require high flexibility together with good mechanical stability at elevated temperatures and high weathering resistance. A number of proposals for thermoplastic olefin films of this type are disclosed.
US 2006/0046084 describes a thermoplastic polyolefin roofing membrane produced from a mixture of a polypropylene-based elastomer (PBE) and polyolefin copolymers.
US 2010/0255739 describes a roofing membrane with a composition comprising a propylene-based elastomer.
US 2010/0197844 describes a thermoplastic olefin membrane for use in construction materials which comprises a polypropylene-based elastomer.
However, known thermoplastic polyolefin films do not yet have a satisfactory combination of mechanical properties, for example, for use as roofing membranes.
Also disclosed are specific reactor blends, a particular example being the “Hifax” material from LyondellBasell. Although these feature good mechanical properties for use as thermoplastic polyolefin roofing membranes they have the disadvantage of being very costly.
The attempts made hitherto to provide materials which have properties of this type but are less costly have not been successful. In traditional mixtures, an at least semicrystalline polyolefin material such as polyethylene or polypropylene, which provides the mechanical strength and resistance to temperature change, is mixed with a flexible blend component. This flexible blend component is miscible, or at least compatible, with the polyolefin. Flexible blend components used in the experiments carried out hitherto are, inter alia, ethylene-propylene-diene rubber (EPDM), ethylene-n-alkene copolymers, and also polypropylene-based elastomers. However, the experiments carried out hitherto in this direction have not proven to be successful.